Many refrigerator cabinet designs cause certain surface regions of the cabinet to exhibit a tendency to be chilled below the dew point of the ambient air, such that condensate or "sweat" forms on the surfaces. One such region is located about the door sealing gasket and particularly the freezing compartment door sealing gasket. This condensate is unsightly and may have a deleterious effect on surface finish and even wet the floor areas below these regions and, accordingly, it is sought to be avoided in most refrigerator designs. If these regions are heated so as to be warmed above the dew point temperature of the ambient air, the formation of such condensate is avoided.
One approach which is currently widely practiced is the use of electric resistance heating cables disposed within the refrigerator cabinet panels which are turned on and off as needed to prevent the condensate formation. While it is relatively simple to incorporate and readily controllable by a manual control switch, electric resistance heating increases the power required to operate the appliance. If the heater is not properly located and therefore not in good heat transfer relationship with the cabinet outer surfaces it is not as effective to prevent condensate on the cabinet.
The refrigerator system includes structure which is at a relatively elevated temperature, i.e., the compressor and condenser coil. This relatively warm structure thus represents a possible heat source whenever the compressor is running which does not require an extra energy source. Rather, heat may be utilized which is otherwise merely dissipated into the surrounding room air. It is known to utilize a heat transfer system for utilizing this heat source to heat those regions of the refrigerator cabinet which are subject to the formation of condensate. An example of such a system is found in U.S. Pat. No. 4,158,294.
These systems typically incorporate a so-called "secondary loop" refrigerant circulation system in which a loop of tubing containing fluid material which can act as a refrigerant is placed in contact with relatively warm portions of the refrigerator structure such as the compressor housing or the condenser loop. The relatively warm temperature heats the refrigerant within the secondary loop causing it to be vaporized and passed into the upper regions of the loop, which are located at the cabinetry regions to be warmed. The resultant cooling of the heated refrigerant causes the refrigerant to condense releasing heat to warm the cabinet, the liquid refrigerant flowing back to the warm region in liquid form. Repetition of the cycle allows a relatively effective heat transfer means for utilizing the heat source provided by the warm or hot components of the refrigeration equipment. Such "secondary loop" however needs to be placed correctly in the area of the cabinet to be warmed to be effective, as does the electric resistance heating cable mentioned above, and particularly in the case where insulation material will be put in place in the cabinet subsequent to location of the heater in the cabinet.
By this invention, there is provided a method of assembling an anti-sweat heater of either of the types mentioned above in a refrigerator cabinet that assures that it is properly located in the area of the cabinet to be heated for effective prevention of condensate on the cabinet and retained in that area during the subsequent insulation material placement operation, particularly in the case of foamed-in-place insulation.